Heavy duty v-belt

ABSTRACT

A heavy-duty V-belt is characterized by envelope construction enclosing a stiff fiber-loaded compression section and molded-in transverse corrugations on the inside surface having a depth at the longitudinal center of the belt greater than the envelope material thickness and tapering into the sides of the belt to a depth at least equal to the envelope thickness.

United States Patent 1 1 1111 3,800,610

Wach Apr. 2, 1974 [5 HEAVY DUTY V-BELT 2,392,373 1/1946 Freedlander156/137 2,642,751 6/1953 Freedlander.. 74/233 [75] lnventor. Andrew P.Wach, Lincoln, Nebr. 2615L463 3H9 Waugh 74/233 [73] Assignee: TheGoodyear Tire & Rubber 2,822,856 2/1958 Waugh 156/139 Cmnlmy, AkmmFOREIGN PATENTS OR APPLICATIONS [22] Filed: Sept. 29, 1972 452,65511/1948 Canada 74/233 [21] Appl. No.: 293,684

Primary ExaminerCharles J. Myhre Assistant ExaminerR H. Lazarus [52] US.Cl. 74/233, 74/231 R, 74/231 C, Attorney, Agent, or Brunner; L. 156/137Germain [51] Int. Cl. F16g 5/16 [58] Field of Search 156/137, 138, 139;74/233,

74/231 P, 231 c, 231 R ABSTRACT A heavy-duty V-belt is characterized byenvelope con- [56] References C'ted struction enclosing a stifffiber-loaded compression UNITED STATES PATENTS section and molded-intransverse corrugations on the 2,281,148 4 1942 Freedlander 74/233inside Surface having a depth at the longitudinal 2,189,049 2/1940Ungar..; 74/231 R ter of the belt greater than the envelope material2,847,865 8/1958 Rockoff.. 74/233 thickness and tapering into the sidesof the belt to a 2,941,413 6/1960 Hu ru 74/233 depth at least equal tothe envelope thickness. 2,194,833 3/1940 Nassinbene.... 74/233 2,210,0739/1940 Freedlander 74/233 5 Claims, 3 Drawing Figures HEAVY DUTY V-BELTSUMMARY OF THE INVENTION This invention relates to heavy duty V-typedrive belts commonly used in agricultural combine traction and cylinderdrive applications. Because of the harsh environmental operatingconditions, the high loads encountered, and the high rate of wear, beltsof this type are generally made thicker, having a lower ratio of topwidth to belt thickness and are usually covered with a heavy cordedfabric envelope or jacket. This heavyduty V-belt design results in astiff cross-section with potentially high stress planes at the bottom ofthe compression-section cushion and at the bottom of the envelope, anddevelop what is referred to in the art as bottom cracking." Bottomcracking may start at either of these stress planes and with the cordfabric envelope construction the bottom cracking may begin at the bottomof the cushion rather than at the bottom of the envelope. This situationleaves the fabric on the bottom of the belt virtually useless. In thepast, for this type of belt and particular application, manufacturershave relied on the toughness of the envelope and cushion material toprovide a belt exhibiting good belt life. However, with recent increasesin drive acceleration and speed and decreases in running diameters, thebelts used in these heavy-duty applications began exhibiting a markeddecrease in belt-life due to bottom cracking. Therefore, it is a primaryobject of this invention to provide a V-type fabric wrapped belt forextremely heavy-duty and aggressive applications with improvedflex-fatigue or bottom-cracking characteristics. It is another object ofthis invention to provide a belt having a reduced stress build-up withinthe belt resulting in a reduction in hysteresis losses and a subsequentreduction in internal belt temperature. This temperature reductionultimately results in a belt having increased belt life.

DESCRIPTION OF THE DRAWINGS The features of the invention will be betterunderstood from a consideration of the following description taken inconjunction with the accompanying drawings in which:

FIG. 1 is a perspective, sectional view of the belt of this invention;

FIG. 2 is a cross-sectional, elevational end view of the belt of FIG. 1;and

FIG. 3 is a cross-sectional, elevational side view taken on line 33 ofFIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the drawings,there is illustrated a V-belt construction generally indicated at whichcomprises tension, neutral axis, and compression sections indicated byl2, l4, and 16, respectively. The neutral axis section 14 is composed ofa plurality of Iongitudinally oriented and substantially inextensible,tightly twisted cords 18 embedded in a tough rubber compound 20. Theneutral axis section 14 is bounded on the bottom by the compressionsection 16 composed of a stiff, fiber-loaded rubber cushion compound toprovide transverse stiffness to the belt, and on the top by the tensionsection 12 composed of a rubberimpregnated fabric envelope 22 toaccommodate longitudinal belt flexure. The entire belt structure iswrapped in the heavy rubber-impregnated fabric envelope 22 that is shownas a single ply but may as well be multiple plies and may be composed ofeither a tire cord fabric or a square woven fabric. The combination ofelements just described provides a belt having a very stiff crosssection resulting in potentially high stress planes at the bottom of thecompression section 16a and at the bottom of the envelope 18a. To breakup the stress concentrations, corrugations 24 are incorporated into thebottom of the belt during vulcanization. These corrugations aremolded-in transverse to the length of the belt and have a depth 240 atthe longitudinal center of the belt 26 greater than the envelopematerial thickness and taper into the sides of the belt 28 to a depth24b at least equal to the envelope material thickness. Thesecorrugations break up the straight line stresses developed in the beltby increasing the actual length of the inside surface of the compressionsection cushion and the envelope. The stress concentrations will now bedeveloped in the corrugations 24 which are dimensionally closer to thebelts neutral axis section 14 and thus are reduced in intensity. Asherebefore mentioned, bottom cracking with this heavy-duty constructioncan and often does start at the bottom of the compression cushion 16arather than at the bottom of the envelope 18a, leaving the envelopefabric on the bottom of the belt virtually useless, but with thecorrugations as described, the envelope fabric is transferred from thebottom of the trapezoidal section of the V-belt to the profile of thecorrugations. This transformation places the fabric in the corrugationssubject to application flexure stresses and thus relieves the flexurestresses on the adjacent cushion compound. In addition, the placement ofthe fabric in the corrugations aids in the retardation of flexurecracking in the corrugations.

It should be emphasized that the corrugations herebefore described arenot cogs, notches, or teeth, as these terms are used in the art toprovide increased belt flexibility. The corrugations of this inventionare deeper at the longitudinal center of the belt 26 than at the sides28 having a preferred range at the center between 10-35 percent of thebelt thickness. Tests conducted on this belt indicated that corrugationsless than 10 percent of the belt thickness are in the range of theenvelope material thickness and have as much effect on bottom cracking"as a similar belt with no corrugations. In contrast to cogs or teeththat are cut or molded at an equal depth across the belt width, thecorrugations of this invention are tapered into the sides of the belt,being of lesser depth 24b at the sides resulting in a substantialincrease in sidewall area 28. Since the same stresses that affect theinside surface of the belt also affect the lower half of the sidewall,the stresses are distributed over a larger area with a markedimprovement in sidewall degradation.

Although the invention may be applied to any type belt, it isparticularly shown and described with reference to belts used inheavy-duty applications. With this in mind, it should be noted that thetransverse crosssectional configuration of the belt, as illustrated inFIGS. 1 and 2, is an arched construction under noload. Since these beltsare used for extremely vigorous applications, they tend to be wider andare built in an arched or arcuate configuration to provide loadtransferto the central portion of the belt and limit transverse bending underload."

While only a single representative embodiment of the invention has beenshown in detail and described, it will become apparent to those skilledin the art that various changes and modifications may be made thereinwithout departing from the spirit or scope of the invention as coveredby the appended claims.

What is claimed is:

1. An arched transverse section, low-ratio top width to thickness V-typebelt exhibiting longitudinal and travsverse stiffness comprising:

a. a tension section;

b. a substantially inextensible neutral axis section below the tensionsection;

c. a compression section below the neutral axis section; and

d. a fabric envelope enclosing the tension, neutral axis, andcompression sections, said belt having molded therein a plurality ofsubstantially evenly spaced transverse corrugations on the inside sur-2. The belt of claim 1, wherein the corrugations are within the range of-35 percent of the total belt thickness.

3. The belt of claim 1, wherein the compression section comprises afiber-loaded rubber to provide transverse stiffness to the belt.

4. The belt of claim 3, wherein the envelope is a tire cordrubber-impregnated fabric.

5. The belt of claim 3, wherein the envelope is a square-woven,rubber-impregnated fabric.

1. An arched transverse section, low-ratio top width to thickness V-typebelt exhibiting longitudinal and travsverse stiffness comprising: a. atension section; b. a substantially inextensible neutral axis sectionbelow the tension section; c. a compression section below the neutralaxis section; and d. a fabric envelope enclosing the tension, neutralaxis, and compression sections, said belt having molded therein aplurality of substantially evenly spaced transverse corrugations on theinside surface thereof having a depth at the longitudinal center of thebelt greater than the envelope material thickness and tapering into thesides to a depth at least equal to the envelope material thickness saidcorrugations effectively relieving the flexure stresses at the bottom ofthe compression section without adding appreciable flexibility to thebelt.
 2. The belt of claim 1, wherein the corrugations are within therange of 10-35 percent of the total belt thickness.
 3. The belt of claim1, wherein the compression section comprises a fiber-loaded rubber toprovide transverse stiffness to the belt.
 4. The belt of claim 3,wherein the envelope is a tire cord rubber-impregnated fabric.
 5. Thebelt of claim 3, wherein the envelope is a square-woven,rubber-impregnated fabric.